BOSTON — Long after Wei-Yin Chen had ended his flirtation with a perfect game, his manager had to answer questions about how a blowout win almost went south.
“Winning a major league game is never easy,” Baltimore manager Buck Showalter said after the Orioles, ahead 10-1 in the ninth inning, yielded five runs to the Red Sox but hung on for a 10-6 victory.
The Orioles reduced their magic number for clinching the American League East for the first time since 1997 to eight.
“It’s a grind every night,” Showalter said. “In the major leagues, there’s too much power spread throughout the lineups.”
The Orioles completed a sweep of the three-game series and raised their record to 44-20 since June 30.
With two on and two out, right-hander Darren O’Day, the third pitcher of the inning, got the last out for his third save.
Chen, winning his 15th game, retired the first 16 hitters before rookie catcher Dan Butler, collecting his first major-league hit in 13 at-bats, doubled off the wall in left-center.
Chen (15-4), with one loss since June 28, gave up a leadoff home run to shortstop Xander Bogaerts, his 11th of the season, in the seventh.
The left-hander then gave up a double to designated hitter David Ortiz and retired the next three hitters, the last two on strikeouts, and was done for the day.
Butler added a second double in the eighth and a single in the ninth, Boston’s only single among its eight hits.
Bogearts ripped his second hit, a double, in the ninth, when the Red Sox rallied against left-hander Joe Saunders — on a two-run double by right fielder Daniel Nava and three on the first career home run by third baseman Carlos Rivero.
Then Bogaerts made the last out with two men on.
Shortstop Ryan Flaherty of Portland had a career-high four hits, two in a six-run third inning, to lead a 15-hit attack for the Orioles.
Center fielder Adam Jones, who had three hits, grounded a two-run double down the left field line to highlight the big inning against right-hander Brandon Workman (1-9), who has nine straight losses, eight of them in starts.
Catcher Caleb Joseph, who also had three hits, hit a two-run shot, his ninth home run of the season, in the fifth as the Orioles raised their record against the Red Sox to 34-19 since 2012.
Boston, mired in last place in the division, lost its fourth straight, falling to a season-worst 20 games under .500 — and was officially eliminated from playoff contention.
On Tuesday night, Alejandro De Aza posted his second two-homer performance of the season and Adam Jones also went deep as the Orioles won 4-1.
Chris Tillman (12-5) extended his unbeaten streak to 11 starts by allowing a run and six hits over five innings for the Orioles. De Aza finished with three hits and three RBIs as he homered twice for the first time since the Chicago White Sox’s season opener on March 31.
Xander Bogaerts went 2-for-3 with a home run for the Red Sox. Anthony Ranaudo (3-2) had a somber 25th birthday as he surrendered four runs and six hits in 3 1/3 frames.
Baltimore took a 2-0 lead before an out was recorded as Nick Markakis led off the game with a walk and De Aza followed with a shot to right field. The Orioles doubled the advantage two innings later, when De Aza — who is 8-for-20 in five games since being acquired from Chicago — and Jones opened the third with back-to-back blasts.
After leaving runners on second and third in their half of the frame, the Red Sox got on the board in the fourth as Bogaerts belted a two-out solo shot to left. Boston threatened again in the fifth as it loaded the bases with one out before David Ortiz grounded into an inning-ending double play, and Bogaerts was thrown out at the plate in the ninth.